1. Technical Field
The present invention relates to a piezoelectric generator, a sensor node, and a method of manufacturing a piezoelectric generator.
2. Related Art
There has been known a piezoelectric generator provided with a cantilevered piezoelectric transducer, and generating electric energy due to the piezoelectric effect caused by the vibration of the piezoelectric transducer (see, e.g., JP-A-11-18445 (Document 1)). The piezoelectric generator described in Document 1 is provided with a support member disposed under the piezoelectric transducer (a first electrode, a piezoelectric thin film, and a second electrode), the support member having a deformable section deformed in accordance with the piezoelectric transducer, and a support section for supporting the deformable section. Such a piezoelectric generator is manufactured by depositing various layers such as a sacrificial layer, a support layer, two electrode layers, and a piezoelectric body layer on a silicon substrate using a low-pressure deposition process such as a sputtering process or a chemical vapor deposition process, and then patterning it using a photolithography process and an etching process.
There is proposed a sensor network having a number of sensor network terminals (hereinafter referred to as sensor nodes) provided with a communication function installed in various places to thereby form a network, and for collecting the data obtained by each of the sensor nodes. The sensor node, which is provided with a sensor, a circuit, a communication system, and a power source, is required to be small in size and low-profile so as to be easily installed in a variety of places, efficiently generate electricity and operate for a long period of time, and is further required to be provided at low price. As a power source of such a sensor node, use of the piezoelectric generator described above has been considered.
However, the piezoelectric generator described in Document 1 has a configuration that the support member intervenes under the piezoelectric transducer, and the deformable section of the support member vibrates in accordance with the piezoelectric transducer, and therefore, there arises a problem that it is difficult to achieve low-profiling. Since the manufacturing process of the piezoelectric generator requires an expensive vacuum (low-pressure) deposition device, and includes a complicated process using the photolithography process and the etching process, there arises a problem that cost reduction is difficult.